Have not had this issue.

However, you'll generally want Keymaps on, and Repeater off, when you play.
We have two basic broadcast options with IS Boxer.

Repeater, which the wizard configures as Mouse + Keyboard.
Which is useful for entering your passwords, or having them all /wave or /dance.
And is nice for clicking portals with everyone at once etc.

And...

Keymaps, which are very strong macro/hotkeys essentially.
You assign a hotkey to them, targets and actions.
For pretty much most of your actions, which are being repeated to the others....
You would want to set those up as mapped keys.
Keymaps are very flexible and powerful, a strong tool -- you can send to other windows, current window, members of a class, members of a group you've made etc. Independent slave movement, without changing anything in warcraft.

I'd definitely move to using Keymaps for play, with Repeater off.